Means for producing hardened cast iron valve tappets



J. L. DOSTAL 2,008,854

MEANS FOR PRODUCING HARDENED CAST IRON VALVE TAPPETS July 23, 1935.

3 Sheets-Sheet 1 7 Original Filed Sept. 28, 1929 Jose-PH L. DUSTFILlNVENTOR ATTORNEY July 23, 1935. J. L. DOSTAL 2,008,854

MEANS FOR PRODUCING HARDENED CAST IRON VALVE TAPPETS Original FiledSept. 28, 1929 s Sheets-Sheet 2 LET INVENTOR BY W ATTORNEY July 23,1935.

J. L. 'DOSTAL MEANS FOR PRODUCING HARDENED CAST IRON VALVE TAPPETSOriginal. Filed Sept. 28, 1929 3 Sheets-Sheet 3 Elm-5.5-

INVENTOR W ATTORNEY Patented July 23, 1935 UNITED STATES PATENT OFFICEMEANS FoR PRODUCING HARDENED CAST IRON VALVE TAPPETS MichiganApplication September 28, 1929, Serial No. 395,949 Renewed July 15, 19321 Claim.

This invention relates to an improved method of making cast iron tappetsfor use in internal combustion engines and means therefor.

The object of this invention is to produce a cast iron tappet having ahard face and a stem which is not so hard but that the extreme end canbe drilled and tapped for the tappet adjusting screw.

In the drawings:-

Figure 1 shows in elevation a view of the valve tappet casting.

Figure 2 shows in elevation the simplest form of mold in which it ispossible to produce these tappets.

Figure 3 shows a. cross section elevation on plane 3--3 of Figure 2. a

Figure'4 shows in elevation a more elaborate mold which has been foundsatisfactory when large quantities of valve tappets are required.

Figure 5 is a cross section elevation on the plane 5-5 of Figure 4.

Figure 6 is a plane view looking down on Figure 5.

Figure 7 shows a portion of the mold shown in Figure 4.

In Figures 1, 2 and 3, A is the valve tappet stem, B is the hardenedface of the valve tappet, E is the sprue. In Figure 2, C is thepermanent metallic mold having a number of mold cavities DD. EE are thegates into which the metal is poured. K are the cavities below thecavity D in which the mushroom heads of the tappets are formed. F is athermo couple connected through leads G, to an instrument H whichrecords the temperature of the mold at a point as near as possible tothe point where the face B of the valve tappet A solidifies.

The diameter of the valve stem A is approximately and the mean thicknessof the valve tappet is in the head.

The surface of the mold cavity is coated with a thin adherent heatinsulating refractory coating as described in the Meloche Patent No.1,453,- 593. This refractory coating isalso covered with a lamp blackcoating, as described in Patent No. 1,492,694. At K the face isunprotected except by the lamp black coating, the reason for this isthat at this point the head solidifies, and there- .fore the maximumtemperature drop is desired -at this point between the temperature ofthe molten iron and the temperature of the face of the mold, so that therate of cooling shall be sufliciently rapid so that the face of thecasting hardens on solidifying, that is to say that a considerablequantity of carbon is retained in solution.

Figs. 4, 5, 6 and 7, show an improved permanent mold in which each halfis formed of three metallic or other suitable rigid parts comprisingupper portions l and 4 in which the sprues and gate are-formed,intermediate portions 2 and 5 in which the valve tappets are formed, andlower portions 3 and 6 which carry a loose detachable metallic piece I,which is the portion against which the hardened face of the tappetsolidifies. This piece I (Fig. '7) is slotted so as to engage with studs8, these studs are screwed into the lower portion 3 and project throughholes in the corresponding lower piece 6. These studs act as guides forpieces I when molds are open. It will be noted that piece I can readilybe removed and replaced without interrupting producing operations. Theintermediate portion 2 is provided with two perforated ears 9' and Ill,these cars engaged with corresponding pins 9 and In which project fromthe piece 5. The purpose of these pins is to insure that the moldingcavities I3 located in 2 and 5 are in exact alignment. In the upperpieces I and 2 the trough II is provided. This trough suppliesmolteniron to the sprue l2-|2 leading to the cavities l3l3 in which the valvetappets are formed. The lower portions [4-44 of the valve tappetcavities I3-l3 are closedby the loose piece I.

A thermo couple I5 is located in this piece 1 and connected throughleads Hi to an instrument l1, so that the temperature of the piece I canbe maintained within a few degrees of 350 F., say between 300 and 400 F.

Operation-The molds are mounted in any convenient molding machine sothat the caviti s of the molds will be in' alignment with each other.

Referring particularly to Fig. 2, a molten cast iron of a type suitablefor chilling as, for example,

having a composition of :2 A. silicon, 3 carbon, .06% manganese, lessthan .1% sulphur and 25% phosphorus is poured into gates EE. By pouringthis iron into the mold the temperature of the mold is raised. Themolten iron exposed to the metallic mold parts cools fasten than does-'that exposed to the refractory material andconsequently forms ahardened region in the tappet casting.

I have discovered that when the temperature I at F is between 300 and400 F. preferably 350, the surface of the iron which-solidifies at K hasa Brinell reading between 300 and 400 R, which is a satisfactory figureto insure long life and little wear.

In Figures 4, 5, 6 and '7, it will be noticed that the cavities on theextreme'right will be filled up before those on the extreme left as theentrances l2 to the cavities l3 are lower on the extreme right than theyare on the extreme left. The

castings are repeatedly made until the temperature on the portions I and4 of the mold exceeds 400 F. or 500' F. and until the temperature of thepart 1 raised above 300, therleliegter the temcontinues uninterrupted.As in Figures 2 the' mold is protected with Meloche coating as shown inUnited States Patents, 1,453,593; 1,492,694; 1,506,130; 1,560,838; and1,568,234 in the trough H, the gates I2, part I3 and the upper portionof H. The surface of 1 against which the face of the tappet solidifiesis, however, unprotected so that the full chilling effect is produced onthe face ll of the tappets. ,In addition to the refractory coating acoating of lamp black is applied, as reierred to in Patent No.1,492,694. The lamp black coating should be renewed between each castingand is also applied to the upper surface of the piece 1,. When thecastings are removed from the mold the tappets are broken ofi from thegates |2-I2 at the shoulder formed at the junction between I! andl3.Provided that the mean'temperature of the mold is kept at 400 or 500 itwill'be possible, I have found, to drill and tap the stem of the valvetappet so that the tappet adjustment screw can be screwed therein.

What I, claim is:

A molding machine adapted to produce cast iron valve tappets, comprisinga three piece metal mold consisting of a matching pair havingsubstantially vertical parting faces, and a third piece which ishorizontal, against which the heads of the valve tappets are adapted tobe cast; a plurality of corresponding mold cavities in the faces of thematching pair of molds, gates each arranged at a different level withrespect=to said third piece and communicating with a connecting channelwhereby the gates are successively fed with molten iron, said cavitiesbeing protected with a thin, adherent refractory, heat insulatingcoating, said horizontal piece being unprotected.

. JOSEPH LOUIS DOSTAL.

